Olbiaspididae is a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of extinct amphiaspidid heterostracan agnathans whose fossils are restricted to Lower Devonian marine strata of

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...

near the Taimyr Peninsula. In life, all amphiaspidids are thought to be benthic animals that lived most of their lives mostly buried in the sediment of a series of hypersaline lagoons. Amphiaspids are easily distinguished from other heterostracans in that all of the plates of the cephalothoracic armor are fused into a single, muff-like unit, so that the forebody of the living animal would have looked, in the case of olbiaspidids, vaguely like a hot water bottle with a pair of small, or degenerated eyes, with each flanked by a preorbital opening, and a simple, slit-like mouth positioned at the anteriormost portion of the cephalothoracic armor. Olbiaspidids differ from the amphiaspidoid amphiaspids of

Amphiaspididae Amphiaspididae is a family of extinct amphiaspidid heterostracan agnathans whose fossils are restricted to Lower Devonian marine strata of Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an ex ...

in that olbiaspidids have wing-like extensions of the cephalothoracic armor that the genera of Amphiaspididae lack, and differ from amphiaspidoid amphiaspids of Gabreyaspididae in that gabreyaspidids' mouths are ventrally positioned, whereas the mouths of olbiaspidids are positioned anteriorly.

Taxonomy

''Olbiaspis''

This is the type genus of the family, and has two species, ''O. coalescens'', and ''O. latissima''. ''O. coalescens'' resembles a hot water bottle with dorso-anteriorly positioned small eyes flanked by preorbital openings, and a prominent dorsal spine, while ''O. latissima'' is extremely broad in comparison.

''Kureykaspis''

''Kureykaspis salebrosa'' has a compact cephalothoracic armor that is pear-shaped (when viewed from above), and that is decorated with distinctive ridges and nodules. The armor has lateral wings with serrated edges. The dorsal spine is vestigial or lacking.

''Angaraspis''

''Angaraspis urvantzevi'' differs from other olbiaspidids in having a rhomboid-shaped cephalothoracic armor. Like ''Olbiaspis'', ''A. urvantzevi'' has a prominent dorsal spine.

References

Amphiaspidida Devonian jawless fish Early Devonian fish Prehistoric jawless fish families Devonian fish of Asia Fauna of Siberia Fossils of Russia Early Devonian first appearances Devonian extinctions {{Devonian-jawless-fish-stub